         definition (read-definition dataset)
         concepts (read-concepts definition)]
     (with-db (get-db dataset)
+      (coll/drop slice)      
       (load-slice slice concepts definition)
       (index-slice slice definition))))

    (when (and drakefile (.isFile drakefile))
      (run-drakefile drakefile))))

(defn ez-load-concepts
  "Load just the concepts for a dataset.
  Does not run Drake to process data first."

        group-id (apply merge
                        (map #(hash-map % (str "$" (name %))) dimensions))
        aggs (map (fn [[agg-metric [agg metric]]]
                    (if (= agg "count")
                      {agg-metric {"$sum" 1}}
                      {agg-metric {(str "$" (name agg))
                                   (str "$" (name metric))}})) aggregations)
        group (apply merge {:_id group-id} aggs)
        project-dims (map (fn [dimension]
                            {dimension
